Report current operation when coercion fails

This makes for a more actionable error message.

Author: findepi

datafusion/expr/src/type_coercion/functions.rs

@@ -64,7 +64,12 @@ pub fn data_types_with_scalar_udf(
         return Ok(current_types.to_vec());
     }
 
-    try_coerce_types(valid_types, current_types, &signature.type_signature)
+    try_coerce_types(
+        func.name(),
+        valid_types,
+        current_types,
+        &signature.type_signature,
+    )
 }
 
 /// Performs type coercion for aggregate function arguments.
@@ -100,7 +105,12 @@ pub fn data_types_with_aggregate_udf(
         return Ok(current_types.to_vec());
     }
 
-    try_coerce_types(valid_types, current_types, &signature.type_signature)
+    try_coerce_types(
+        func.name(),
+        valid_types,
+        current_types,
+        &signature.type_signature,
+    )
 }
 
 /// Performs type coercion for window function arguments.
@@ -133,7 +143,12 @@ pub fn data_types_with_window_udf(
         return Ok(current_types.to_vec());
     }
 
-    try_coerce_types(valid_types, current_types, &signature.type_signature)
+    try_coerce_types(
+        func.name(),
+        valid_types,
+        current_types,
+        &signature.type_signature,
+    )
 }
 
 /// Performs type coercion for function arguments.
@@ -144,6 +159,7 @@ pub fn data_types_with_window_udf(
 /// For more details on coercion in general, please see the
 /// [`type_coercion`](crate::type_coercion) module.
 pub fn data_types(
+    operation: impl AsRef<str>,
     current_types: &[DataType],
     signature: &Signature,
 ) -> Result<Vec<DataType>> {
@@ -166,7 +182,12 @@ pub fn data_types(
         return Ok(current_types.to_vec());
     }
 
-    try_coerce_types(valid_types, current_types, &signature.type_signature)
+    try_coerce_types(
+        operation,
+        valid_types,
+        current_types,
+        &signature.type_signature,
+    )
 }
 
 fn is_well_supported_signature(type_signature: &TypeSignature) -> bool {
@@ -187,6 +208,7 @@ fn is_well_supported_signature(type_signature: &TypeSignature) -> bool {
 }
 
 fn try_coerce_types(
+    operation: impl AsRef<str>,
     valid_types: Vec<Vec<DataType>>,
     current_types: &[DataType],
     type_signature: &TypeSignature,
@@ -218,7 +240,8 @@ fn try_coerce_types(
 
     // none possible -> Error
     plan_err!(
-        "Coercion from {:?} to the signature {:?} failed.",
+        "{}: coercion from {:?} to the signature {:?} failed.",
+        operation.as_ref(),
         current_types,
         type_signature
     )
@@ -971,23 +994,23 @@ mod tests {
             Volatility::Stable,
         );
 
-        let coerced_data_types = data_types(&current_types, &signature).unwrap();
+        let coerced_data_types = data_types("test", &current_types, &signature).unwrap();
         assert_eq!(coerced_data_types, current_types);
 
         // make sure it can't coerce to a different size
         let signature = Signature::exact(
             vec![DataType::FixedSizeList(Arc::clone(&inner), 3)],
             Volatility::Stable,
         );
-        let coerced_data_types = data_types(&current_types, &signature);
+        let coerced_data_types = data_types("test", &current_types, &signature);
         assert!(coerced_data_types.is_err());
 
         // make sure it works with the same type.
         let signature = Signature::exact(
             vec![DataType::FixedSizeList(Arc::clone(&inner), 2)],
             Volatility::Stable,
         );
-        let coerced_data_types = data_types(&current_types, &signature).unwrap();
+        let coerced_data_types = data_types("test", &current_types, &signature).unwrap();
         assert_eq!(coerced_data_types, current_types);
 
         Ok(())

datafusion/optimizer/src/analyzer/type_coercion.rs

@@ -1357,7 +1357,7 @@ mod test {
 
         let err = Projection::try_new(vec![udaf], empty).err().unwrap();
         assert!(
-            err.strip_backtrace().starts_with("Error during planning: Error during planning: Coercion from [Utf8] to the signature Uniform(1, [Float64]) failed")
+            err.strip_backtrace().starts_with("Error during planning: Error during planning: MY_AVG: coercion from [Utf8] to the signature Uniform(1, [Float64]) failed")
         );
         Ok(())
     }
@@ -1407,7 +1407,7 @@ mod test {
             .err()
             .unwrap()
             .strip_backtrace();
-        assert!(err.starts_with("Error during planning: Error during planning: Coercion from [Utf8] to the signature Uniform(1, [Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Float32, Float64]) failed."));
+        assert!(err.starts_with("Error during planning: Error during planning: avg: coercion from [Utf8] to the signature Uniform(1, [Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Float32, Float64]) failed."));
         Ok(())
     }